Materials and noncoplanar mesh designs for integrated circuits with linear elastic responses to extreme mechanical deformations

Abstract

Electronic systems that offer elastic mechanical responses to highstrain deformations are of growing interest because of their ability to enable new biomedical devices and other applications whose requirements are impossible to satisfy with conventional wafer-based technologies or even with those that offer simple bendability. This article introduces materials and mechanical design strategies for classes of electronic circuits that offer extremely high stretchability, enabling them to accommodate even demanding configurations such as corkscrew twists with tight pitch (e.g., 90°in Ϸ1 cm) and linear stretching to ''rubber-band'' levels of strain (e.g., up to Ϸ140%). The use of single crystalline silicon nanomaterials for the semiconductor provides performance in stretchable complementary metal-oxide-semiconductor (CMOS) integrated circuits approaching that of conventional devices with comparable feature sizes formed on silicon wafers. Comprehensive theoretical studies of the mechanics reveal the way in which the structural designs enable these extreme mechanical properties without fracturing the intrinsically brittle active materials or even inducing significant changes in their electrical properties. The results, as demonstrated through electrical measurements of arrays of transistors, CMOS inverters, ring oscillators, and differential amplifiers, suggest a valuable route to high-performance stretchable electronics.flexible electronics ͉ stretchable electronics ͉ semiconductor nanomaterials ͉ plastic electronics ͉ buckling mechanics I ncreasingly important classes of application exist for electronic systems that cannot be formed in the usual way, on semiconductor wafers. The most prominent example is in large-area electronics (e.g., back planes for liquid crystal displays), where overall system size rather than operating speed or integration density, is the most important metric. Similar systems that use flexible substrates are presently the subject of widespread research and commercialization efforts because of advantages that they offer in durability, weight, and ease of transport/use (1, 2). Stretchable electronics represents a fundamentally different and even more challenging technology, of interest for its unique ability to flex and conform to complex curvilinear surfaces such as those of the human body. Several promising approaches exist, ranging from the use of stretchable interconnects between rigid amorphous silicon devices (3) to ''wavy'' layouts in singlecrystalline silicon CMOS circuits (4), both on elastomeric substrates, to net-shaped structures in organic electronics on plastic sheets (5). None offers, however, the combination of electrical performance (high electron and hole mobility), scalability (with relatively modest modifications to conventional microelectronic technologies), integrated circuit applicability in complementary designs and mechanical properties required of some of the most demanding, and most interesting, systems. Here, we introduce design concepts for stretchable electronics th...

Photo-patternable and transparent films using cellulose nanofibers for stretchable origami electronics

“…To achieve this functionality, we suggest a patternable and foldable substrate using our CNF hybrid film. Although many previous studies have reported on stretchable interconnects using graphene, 35 metal nanowires, 36 metal nanofiber, 37,38 and geometrical approaches, 39 conventional electronic devices fabricated on the elastomeric substrate are easily broken because most of the semiconductor, dielectric and encapsulation materials are still brittle. Therefore, the approach using origami substrates made of strain-free rigid plates with reversibly foldable and stretchable, elastomeric joints 40 has been considered as a promising strategy for stretchable electronics.…”

A highly stretchable, helical copper nanowire conductor exhibiting a stretchability of 700%

“…To date, two primary strategies have been suggested for the fabrication of stretchable electronic parts apart from complex lithography-based approaches that can shape inorganic conductive materials or metals into buckled geometries, including island-bridge systems. [6][7][8][9] The first strategy is the inclusion of micro-or nano-scale conductive carbon materials into elastic polymer matrices. 1,[10][11][12][13] For example, carbon-based materials, such as carbon nanotubes and graphene, have been extensively researched for stretchable/foldable conductors.…”

A curvy, stretchy future for electronics

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“…work involves characterizing the microscopic behavior of the material structures, the devices, circuits, and systems, where the length scales for the relevant deformations range from millimeters to nanometers (8,10,12,(14)(15)(16). Fig.…”